name : generic-non-atomic.h /* SPDX-License-Identifier: GPL-2.0-only */ #ifndef __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H #define __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H #include <linux/bits.h> #include <asm/barrier.h> #ifndef _LINUX_BITOPS_H #error only <linux/bitops.h> can be included directly #endif /* * Generic definitions for bit operations, should not be used in regular code * directly. */ /** * generic___set_bit - Set a bit in memory * @nr: the bit to set * @addr: the address to start counting from * * Unlike set_bit(), this function is non-atomic and may be reordered. * If it's called on the same region of memory simultaneously, the effect * may be that only one operation succeeds. */ static __always_inline void generic___set_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); *p |= mask; } static __always_inline void generic___clear_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); *p &= ~mask; } /** * generic___change_bit - Toggle a bit in memory * @nr: the bit to change * @addr: the address to start counting from * * Unlike change_bit(), this function is non-atomic and may be reordered. * If it's called on the same region of memory simultaneously, the effect * may be that only one operation succeeds. */ static __always_inline void generic___change_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); *p ^= mask; } /** * generic___test_and_set_bit - Set a bit and return its old value * @nr: Bit to set * @addr: Address to count from * * This operation is non-atomic and can be reordered. * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */ static __always_inline bool generic___test_and_set_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); unsigned long old = *p; *p = old | mask; return (old & mask) != 0; } /** * generic___test_and_clear_bit - Clear a bit and return its old value * @nr: Bit to clear * @addr: Address to count from * * This operation is non-atomic and can be reordered. * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */ static __always_inline bool generic___test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); unsigned long old = *p; *p = old & ~mask; return (old & mask) != 0; } /* WARNING: non atomic and it can be reordered! */ static __always_inline bool generic___test_and_change_bit(unsigned long nr, volatile unsigned long *addr) { unsigned long mask = BIT_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); unsigned long old = *p; *p = old ^ mask; return (old & mask) != 0; } /** * generic_test_bit - Determine whether a bit is set * @nr: bit number to test * @addr: Address to start counting from */ static __always_inline bool generic_test_bit(unsigned long nr, const volatile unsigned long *addr) { /* * Unlike the bitops with the '__' prefix above, this one *is* atomic, * so `volatile` must always stay here with no cast-aways. See * `Documentation/atomic_bitops.txt` for the details. */ return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); } /** * generic_test_bit_acquire - Determine, with acquire semantics, whether a bit is set * @nr: bit number to test * @addr: Address to start counting from */ static __always_inline bool generic_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr) { unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1))); } /* * const_*() definitions provide good compile-time optimizations when * the passed arguments can be resolved at compile time. */ #define const___set_bit generic___set_bit #define const___clear_bit generic___clear_bit #define const___change_bit generic___change_bit #define const___test_and_set_bit generic___test_and_set_bit #define const___test_and_clear_bit generic___test_and_clear_bit #define const___test_and_change_bit generic___test_and_change_bit #define const_test_bit_acquire generic_test_bit_acquire /** * const_test_bit - Determine whether a bit is set * @nr: bit number to test * @addr: Address to start counting from * * A version of generic_test_bit() which discards the `volatile` qualifier to * allow a compiler to optimize code harder. Non-atomic and to be called only * for testing compile-time constants, e.g. by the corresponding macros, not * directly from "regular" code. */ static __always_inline bool const_test_bit(unsigned long nr, const volatile unsigned long *addr) { const unsigned long *p = (const unsigned long *)addr + BIT_WORD(nr); unsigned long mask = BIT_MASK(nr); unsigned long val = *p; return !!(val & mask); } #endif /* __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H */